MIMO system with multiple spatial multiplexing modes

Abstract

A MIMO system supports multiple spatial multiplexing modes for improved performance and greater flexibility. These modes may include (1) a single-user steered mode that transmits multiple data streams on orthogonal spatial channels to a single receiver, (2) a single-user non-steered mode that transmits multiple data streams from multiple antennas to a single receiver without spatial processing at a transmitter, (3) a multi-user steered mode that transmits multiple data streams simultaneously to multiple receivers with spatial processing at a transmitter, and (4) a multi-user non-steered mode that transmits multiple data streams from multiple antennas (co-located or non co-located) without spatial processing at the transmitter(s) to receiver(s) having multiple antennas. For each set of user terminal(s) selected for data transmission on the downlink and/or uplink, a spatial multiplexing mode is selected for the user terminal set from among the multiple spatial multiplexing modes supported by the system.

What is claimed is: 
     
       1. A method of processing data in a multiple-input multiple-output (MIMO) communication system, comprising:
 generating, at an apparatus, an uplink channel response matrix for each of a plurality of transmitting entities; 
 deriving a steering vector for each of the transmitting entities by decomposing the channel response matrix to obtain a plurality of eigenvectors and a plurality of singular values, and forming the steering vector for each transmitting entity based on an eigenvector corresponding to a largest singular value among the plurality of singular values; 
 evaluating different sets of the transmitting entities and selecting a best set for transmission and reception; 
 sending, to each transmitting entity in the selected best set, a rate selected based on the steering vector and the channel response matrix; and 
 sending the steering vector to each transmitting entity in the selected best set for use in spatially processing data symbol streams to be transmitted to the apparatus from a plurality of transmit antennas at the transmitting entity. 
 
     
     
       2. The method of  claim 1 , further comprising:
 obtaining received symbol streams for the data symbol streams transmitted from the at least some of the transmitting entities; and 
 processing the received symbol streams in accordance with a receiver spatial processing technique to obtain recovered data symbol streams, which are estimates of the data symbol streams. 
 
     
     
       3. The method of  claim 2 , wherein the receiver spatial processing technique is a channel correlation matrix inversion (CCMI) technique or a minimum mean square error (MMSE) technique. 
     
     
       4. The method of  claim 2 , wherein the receiver spatial processing technique is a successive interference cancellation (SIC) technique. 
     
     
       5. The method of  claim 1 , wherein the steering vector for the transmitting entity is equal to the eigenvector corresponding to the largest singular value. 
     
     
       6. An apparatus in a multiple-input multiple-output (MIMO) communication system, the apparatus comprising:
 at least one processor configured to: 
 generate an uplink channel response matrix for each of a plurality of transmitting entities; 
 derive a steering vector for each of the transmitting entities by decomposing the channel response matrix to obtain a plurality of eigenvectors and a plurality of singular values, and forming the steering vector for each transmitting entity based on an eigenvector corresponding to a largest singular value among the plurality of singular values; 
 evaluate different sets of the transmitting entities and select a best set for transmission and reception; 
 send a rate to each of the transmitting entities in the selected best set, the rate selected based on the steering vector and the channel response matrix; and 
 send the steering vector to each of the transmitting entities for use in spatially processing data symbol streams to be transmitted to the apparatus from a plurality of transmit antennas at the transmitting entity. 
 
     
     
       7. The apparatus of  claim 6 , wherein the at least one processor is further to obtain received symbol streams for the data symbol streams transmitted from at least some of the transmitting entities and process the received symbol streams in accordance with a receiver spatial processing technique to obtain recovered data symbol streams, which are estimates of the data symbol streams. 
     
     
       8. The apparatus of  claim 7 , wherein the receiver spatial processing technique is a channel correlation matrix inversion (CCMT) technique or a minimum mean square error (MMSE) technique. 
     
     
       9. The apparatus of  claim 7 , wherein the receiver spatial processing technique is a successive interference cancellation (SIC) technique. 
     
     
       10. The apparatus of  claim 6 , wherein the steering vector for the transmitting entity is equal to the eigenvector corresponding to the largest singular value. 
     
     
       11. An apparatus in a multiple-input multiple-output (MIMO) communication system, comprising:
 means for generating an uplink channel response matrix for each of a plurality of transmitting entities; 
 means for deriving a steering vector for each of the transmitting entities by decomposing the channel response matrix to obtain a plurality of eigenvectors and a plurality of singular values, and forming the steering vector for each transmitting entity based on an eigenvector corresponding to a largest singular value among the plurality of singular values; 
 means for evaluating different sets of the transmitting entities and selecting a best set for transmission and reception; 
 means for sending, to each transmitting entity in the selected best set, a rate selected based on the steering vector and the channel response matrix; and 
 means for sending the steering vector to each transmitting entity in the selected best set for use in spatially processing data symbol streams to be transmitted to the apparatus from a plurality of transmit antennas at the transmitting entity. 
 
     
     
       12. The apparatus of  claim 11 , further comprising:
 means for obtaining received symbol streams for the data symbol streams transmitted from at least some of the transmitting entities; and 
 means for processing the received symbol streams in accordance with a receiver spatial processing technique to obtain recovered data symbol streams, which are estimates of the data symbol streams. 
 
     
     
       13. The apparatus of  claim 12 , wherein the receiver spatial processing technique is a channel correlation matrix inversion (CCMI) technique or a minimum mean square error (MMSE) technique. 
     
     
       14. The apparatus of  claim 12 , wherein the receiver spatial processing technique is a successive interference cancellation (SIC) technique. 
     
     
       15. The apparatus of  claim 11 , wherein the steering vector for the transmitting entity is equal to the eigenvector corresponding to the largest singular value. 
     
     
       16. A computer-program product in a multiple-input multiple-output (MIMO) communication system comprising a non-transitory computer readable medium having instructions thereon, the instructions comprising:
 code for generating, at an apparatus, an uplink channel response matrix for each of a plurality of transmitting entities; 
 code for deriving a steering vector for each of the transmitting entities by decomposing the channel response matrix to obtain a plurality of eigenvectors and a plurality of singular values, and forming the steering vector for each transmitting entity based on an eigenvector corresponding to a largest singular value among the plurality of singular values; 
 code for evaluating different sets of the transmitting entities and selecting a best set for transmission and reception; 
 code for sending, to each transmitting entity in the selected best set, a rate selected based on the steering vector and the channel response matrix; and 
 code for sending the steering vector to each transmitting entity in the selected best set for use in spatially processing data symbol streams to be transmitted to the apparatus from a plurality of transmit antennas at the transmitting entity. 
 
     
     
       17. The computer-program product of  claim 16 , further comprising:
 code for obtaining received symbol streams for the data symbol streams transmitted from at least some of the transmitting entities; and 
 code for processing the received symbol streams in accordance with a receiver spatial processing technique to obtain recovered data symbol streams, which are estimates of the data symbol streams. 
 
     
     
       18. The computer-program product of  claim 17 , wherein the receiver spatial processing technique is a channel correlation matrix inversion (CCMI) technique or a minimum mean square error (MMSE) technique. 
     
     
       19. The computer-program product of  claim 17 , wherein the receiver spatial processing technique is a successive interference cancellation (SIC) technique. 
     
     
       20. The computer-program product of  claim 16 , wherein the steering vector for the transmitting entity is equal to the eigenvector corresponding to the largest singular value.